The difference between D implementing f and D implementing f' is one of interpretation: the states of D, or aspects thereof, are interpreted as symbolic vehicles whose semantic content pertains to the formal specification of either f or f'.

This is nonsense. I'm a computer programmer, and there is a literal, practical, real difference between implementing f and f'. This is true regardless of whether the outputs are the same for a given input. An obvious example is sorting; there are a numerous different algorithms all of which produce the same output: a sorted list. Quicksort, Mergesort, Insertion Sort, Bubble Sort, Stoogesort. However they differ internally quite a bit, and operate quite a bit differently despite producing the same output, going through states that are entirely and objectively distinct from one another. The differences between them are NOT merely a matter of 'interpretation'.

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Originally Posted by Half Man Half Wit

By specification, whether B implements CM is thus due to the particulars of CM.

Hence, computationalism lapses into vicious circularity.

I'm not seeing any circularity, viscious or not. You're basically saying that if you reach into a bag of red and blue balls and happen to pull out the red one, the fact that it's red (as opposed to being blue) is due to the fact it's a red one. It's not a particularly helpful observation, but it's not circular in any sort of problematic way.

Or to put it in terms of computational processess, if you have two physically identical machines, one of which is running Quicksort and one of which is running Stoogesort, then the only thing that is making the Quicksort one the Quicksort one is the fact it's running the Quicksort one. It is distinct from the Stoogesort one (among other things it's a lot faster), but the difference in what it is is indeed a result of it being what it is.

None of this is self-contradictory.

And honestly, even if you were right about computationalism being impossible (which you're not), that doesn't mean that brains can't be copied to computers - it would just mean that it's equally impossible for existing computers to be computational! Which would mean that existing computers are still exactly as capable as brains are to support minds, because none of them are the thing that's impossible. Which makes sense, because existing computers aren't impossible and thus if you prove that something is impossible to do, they're not doing it.

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Originally Posted by Half Man Half Wit

There. I hope that makes things clear. It should, in particular, be obvious now that nothing about the impossible of minds in general is implied; merely, that minds, which clearly do exist, are not computational in nature, that is, are not produced by the brain implementing a certain computation.

Your argument (if it worked, which it doesn't) doesn't just disprove minds being computational - there's nothing about your argument that's specific to mind. It just proves that nothing is computational! Not brains, not computers, nothing! (If the argument worked, which it doesn't.)

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Originally Posted by Half Man Half Wit

Now, I believe you won't give up on the 'but CM just interprets itself'-issue so easily. In that case, I have good news for you, because you can prove the existence of god!

For, god is an omnipotent being. Omnipotence entails the possibility to create gods. Consequently, god may just create him/hir/herself. And that's it!

Logically, this is perfectly analogous to CM interpreting B as computing CM.

It isn't equvalent at all, of course. Your god argument is trying to pull itself up by its bootstraps; the god in question doesn't even exist until it exercises its powers. The brainstate on the other hand does exist. Cognition doesn't predate the brainstate or cause the brainstate; the brainstate exists in the phsyical or simulated realm supported by the phsyical or simulated physics of the world it exists in. Cognition, on the other hand, is the byproduct of the ongoing brain state - the same way that sound is the byproduct of an ongoing vibration in a speaker's membranes.

None of this is analogous to nothing creating something from nothing, none of it is circular, and none of it is self-contradictory.
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